Sanna Markkanen, nine months pregnant and due any day, could not wait. Her husband, Rangers goaltender Jussi, poised to start last night here against the Avalanche, received the call from New York late Wednesday. She was unexpectedly going to deliver the couple’s second child the next day. The father-to-be, who had missed the birth of his first child while on the road playing for the Oilers, asked Glen Sather for permission to fly home for the blessed event.

Permission granted, the goaltender caught the red-eye back to New York, and indeed was present for the birth of his second son at noon yesterday.

“It’s the right thing to do,” Sather said.

So yesterday became one of the most memorable days in Markkanen’s life. Not coincidentally, it also became one of the most memorable days in Jason LaBarbera’s life, too. Because with Mike Dunham still not quite healthy enough to go, the 23-year-old LaBarbera, a fourth-year pro promoted from Hartford on Monday, last night got his first NHL start in goal.

“My head was spinning a little bit when I found out about it around 10:00 [Wednesday] night, said LaBarbera, who had made his NHL debut three years ago with an unscored-upon final 9:43 of an 8-6 loss in Pittsburgh on Oct. 14, 2000. “It’s obviously something I’ve looked forward to my whole life.”

If LaBarbera’s head was spinning before the game, it may well have done a Linda Blair-360 during the match, given the speed with which the Avalanche attacked him throughout most of last night’s 4-3 Ranger defeat. LaBarbera competed, and the defeat that left the tattered Blueshirts with just one win in their last eight games (1-4-2-1), was owed to the many Ranger deficiencies and blunders every bit as much as on their goaltending. It was obvious, however, that the neophyte wasn’t up to the pace of the league, and that his skating and mobility need dramatic improvement.

At least, though, he had an excuse.

But there was no excuse for Greg de Vries repeatedly getting caught out of position. No excuse for team-wide inadequate backchecking. No excuse for a struggling Petr Nedved consistently missing the net from 10 feet. No excuse for Alex Kovalev coughing up the puck in his own end, a blooper that led to the Cody McCormick rebound goal at 17:50 of the second after LaBarbera failed to cover the puck.

That goal came just 1:14 after Steve Konowalchuk drove to the net and scored in strikingly similar fashion on a second rebound with LaBarbera down and unable to smother the puck, a score that provided Colorado with a 3-2 lead.

And there was no excuse for Sather keeping Jamie Lundmark and Jed Ortmeyer pinned to the bench even while the coach kept sending out the veterans who kept making mistakes. But with the Rangers, it’s still who you are, not how you play. Until that changes, nothing else will in New York.

After falling behind 2-0 in the first, the Rangers did pick up their play. They knotted the score when Anson Carter and Martin Rucinsky scored within 3:30 midway through the second.

But though they played with some passion, they did not play well enough against an Avalanche team missing Peter Forsberg and Paul Kariya.

Not nearly well enough, baby.

* Eric Lindros skated yesterday in New York and, barring a setback, is expected to come off IR and rejoin the lineup for Sunday’s Garden match against the Senators. . . . Tom Poti missed the match with a thumb bruise that he suffered in San Jose on Tuesday. He was replaced by Joel Bouchard.